fnsf testing strategy discussions for pfc – pfc/fnsf joint session chairs: maingi, menard, morley...
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FNSF Testing Strategy Discussions for PFC – PFC/FNSF Joint Session
Chairs: Maingi, Menard, Morley
Session Objectives and First Wall Testing Description
Neil Morley, UCLA8/4/2010
Starting Point for this session, a Fusion Nuclear Science Facility – FNSF (CTF, VNS, etc)…
An FNSF facility is proposed as an test facility in which the impact of the integrated fusion environment – Combined plasma particle and heat flux; nuclear heating, damage,
activation; magnetic field and forces; vacuum; and high temperature operation, …
on the operation, performance, and reliability of in-vessel components and systems– Divertor, firstwall/blanket, shields, plasma facing features of
fueling/heating/diagnostic systems, …
can be tested, studied, improved and validated
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Linkages of Main Thrust 13 Elements (Theme IV)
Slide 3
Basic Properties / Separate Effects Testing
Multiple / Partially-Integrated Effects Testing
Integrated Fusion Mockup/Comp Testing
Demo ReadinessDatabase, Design Tools, Qualification / Licensing
Increasing time, complexity, integration, cost
Models and Theory
Simulation Codes
Integration, Benchmarking
The multiple Theme III thrusts also had a similar progression -- ending with testing in a integrated fusion environment
Test Facility Planning & Preparation
ITER-TBM / FNSF Facility and Test Article
Planning, Preparation, Qualification
Decreasing number of concepts and options
The classical fusion “bootstrap” problem…
• To test in a fusion environment, one must be able to create and sustain a fusion environment
• FNSF will to some/large degree require the successful operation of the very components it is supposed to test– How should the basic machine be built?
• How to scale, design, instrument and perform relevant experiments in a reduced scale FNSF that tell us something/everything about DEMO and power plant conditions?
• These questions have led to, in the FNST community meetings over the past 2 years, a discussion of a strategy for first wall / blanket components. We would like to broaden this discussion to include the divertor as well.
Agenda of this joint session
• What divertor material, cooling and configuration options should be considered for FNSF?
• What FNSF parameters and features are required for divertor/PMI testing? What is the PFC/PMI testing strategy in FNSF?
• What R&D is required for the FNSF divertor?
“Base” vs. “Test” First Wall/Blanket
• First wall is integrated into blanket – development, design, analysis and testing must be considered together
• A functioning breeding blanket will be needed to breed tritium during DT operation– no practical or affordable external source is likely available
(~1.6 kg/year burned per 100 MW at 30% availability)
• Consider deployment of a base FW/blanket whose main mission is supply tritium, and port based test FW/blankets that are more easily removable and replaceable and instrumentable
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A FW/Breeding Blanket Testing Strategy
Both port-based and base blanket have a testing mission
Base blanket – Are made largely using the same materials and designs as desired test
blankets, optimized for reliability • Interaction with plasma and neutron field similar to testing blankets
– Should be operated with more conservative temperature margins and smaller temperature gradients
– Can still provide important statistical data on operations and failure modes/effects/rates in all phases DD thru DT operation
Port-based blankets – Are more highly instrumented and designed for specific scientific purposes
and experimental missions– Can be operated with more aggressive and prototypic temperatures and
gradients– Should be designed for fast replacement
What Material Options Exist to Use For Base First Wall / Breeding Blanket
FW and Structural Material: Ferritic/Martensitic steel– Austenitic steel is less suitable because of low thermal stress
factor, high activation, and high swelling. It does not extrapolate to reactor. No reasons found to think that austenitic steel reduces risk.
– Issue of FW armors have not yet been discussed in detail, need PFC/PMI input
Primary Coolant should be Helium, even for base blanket– Most generically reactor relevant, both for ceramic breeder and
dual coolant blanket options– Keep operating temperature of the ferritic structure above 300°C
to minimize the impact of neutron-induced damage.– Potential for chemical reactions between the coolant and the
beryllium or liquid metal breeders can be avoided
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A breeding blanket w/ integrated First Wall should be installed as a BASE Blanket on a FNSF from the beginning
Switching from non-breeding to breeding blanket involves complexity and long downtime, especially if coolant changes from water to helium
There is no non-breeding blanket for which there is more confidence than a breeding blanket (all involve risks, all will require development).
The actual wall conditions and materials used during the DT testing phase – e.g. high temperature and ferritic steel, should also be used during the HH/DD early operation phase in order to:– correctly optimize the plasma performance and pulse length and – obtain actual information on plasma-blanket interactions prior to
DT operations (PMI, first wall heat flux, off-normal events…)Such information is needed for safety/licensing/availability of the DT phase
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Fundamental FNST Research
An intensive program of laboratory scale experiments and model development addressing gaps in understanding and database
Example areas:– PbLi alloy tritium chemistry, transport
characteristics, isotope / impurity control– PbLi compatibility with SiC flow channel
insert material and ferritic/martensitic steel– Liquid metal MHD interactions that
dominate liquid metal blankets and free surface divertors flow and transport
– Heat transfer and enhancement in high-temperature helium-cooled divertor concepts.
– Tritium chemistry, transport and removal techniques from high temperature helium
– Ceramic-breeder pebble-bed response to thermomechanical load and cycling
– Interaction database of beryllium and liquid metal alloys with water and air
Slide 10
An example -- 3D MHD simulation of LM coolant streamlines in a pipe disturbed by a magnetic field gradient
Formation of instabilities and recirculating regions can strongly influence both heat and tritium transport behavior and generate strong flow resistance.
MHD forces generally exceed viscous and inertial forces by 5 orders of magnitude in fusion blankets.
Gradient region
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Fundamental FNST Research (2)
Scope– Functions and Elements of the Blanket,
FW, Divertor, heat transport and tritium systems (mainline and alternates)
– Database, basic phenomena exploration, model development in:
• Thermofluid/Heat transfer properties• Chemistry and reaction rates• Thermomechanical properties• Diagnostic capabilities
– Multiple university/lab research programs
Time scale– Consistent 10 year effort
Other Benefits– Innovation, invention, discovery– Basic validation of existing designs and
models– Reinvigoration of FNST in the US
Slide 11
heater
86mm
86mm
87mm
43mm
64mm
TC
TCLiPb (1 Š 1000 g)In alumina crucible
Alumina crucible
Heat block
Past tritium solubility measurements in PbLi have a wide discrepancy, by orders of magnitude. New experiments must provide better accuracy and help identify sensitivities that can drastically change the results
Objectives of this PFC/FNSF session Similar to first wall/blanket, discuss FNSF objectives, strategy and requirements for testing PFC components •What type of divertors are we considering for DEMO and power plants?
– Are they good candidates for testing in FNSF– How many variations, how should they be tested?– What needs to be shown/observed/measured in divertor testing in FNSF
•What are the possible testing strategies for divertor in FNSF– Can base/test divertors be included (partial toroidal, or upper/lower splits)– Use DD phase for extensive divertor and FW testing– What PMI specific testing is envisioned (maybe independent of first wall or divertor heat
sink design)•What are the requirements on FNSF
– Heating power, access for diagnostics, replacement speed, flexibility in PF coil positioning??
– Accommodate significant quantities of lithium•For these strategies, what is the R&D required in advance of an FNSF
Keep an open mind…
• We asked some people to supply a perspective on some of these questions
• We likely won’t arrive at a definite conclusion today • Try to understand the assumptions and concerns of experts
from PFC and plasma edge• Try to understand how divertor operation and testing can be
done in FNSF• Try to identify the features or parameters of an FNSF that
might be required
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Linkages of Main Thrust 13 Elements (Theme IV)
Slide 14
Basic Properties / Separate Effects Testing
Multiple / Partially-Integrated Effects Testing
Integrated Fusion Mockup/Comp Testing
Demo ReadinessDatabase, Design Tools, Qualification / Licensing
Increasing time, complexity, integration, cost
Models and Theory
Simulation Codes
Integration, Benchmarking
The multiple Theme III thrusts also had a similar progression -- ending with testing in a integrated fusion environment
Test Facility Planning & Preparation
ITER-TBM / FNSF Facility and Test Article
Planning, Preparation, Qualification
Decreasing number of concepts and options
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Multiple-Effects, Synergistic Phenomena
Synergistic phenomena will dominate the behavior, failure modes and reliability of first designs and prototypes. Examples…
– LM Thermofluid/MHD + FCI Thermomechanics– Neutron irradiation driven heating and breeding in blanket
unit cells– Multiple effect tritium/thermal/chemical effects
Utilize test facilities to – explore multiple-effect phenomena,– investigate specific design and material combinations – uncover synergistic failure modes
Partially-integrated thermal, nuclear, electromagnetic, and plasma loading conditions
– Magnetic/Thermal, – Plasma/Thermal, Tritium/Thermal, – Neutron/Thermal/Tritium
that can accommodate prototypic sizes and materials (Be, Li, PbLi, T)
Sufficient single effects database a prerequisite
Slide 15
PMTF-1200 high heat flux facility
MTOR Thermofluid/MHD facility
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Multiple-Effects, Synergistic Phenomena (2)
Slide 16
TPE, in the STAR Tritium Lab
HFIR and ATR Test Reactors
Scope– Mockups of the Blanket, First Wall,
Divertor, heat transport and tritium systems (mainline and alternates)
– Upgrade and construction of needed user test facilities (3-4 total)
Time scale– Planning and scoping - Immediate– Operations, Consistent 10 yr effort
Additional Benefits– Model validation in more complex
operational regimes– Testing fabrication and
diagnostic capability– Initial reliability growth and
qualification information– Enabling continuous power
and tritium extraction